Subantarctic fur seal

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  • 1987/88 Field Season at Heard Island. Harry R. Burton. Field Leader, Antarctic Division. The 1987/88 ANARE to Heard Island was the last of a series of three summer programs there (1985 and 1986/87); and with five and a half months on the Island. It was also the longest. Earth science had been the primary focus of the 1986/87 program. In 1987/88 the focus of the work was again biology, as it had been in 1985; and island transport (other than pedestrian) was by LARC. Nella Dan delivered the party of 17 from September 18 to 20 1987, with four at Spit Bay and the remainder at Atlas Cove. About a month later, on October 18 and 19 she returned: four of the party left and there were two new arrivals, so that 15 people were on the Island until Lady Franklin picked up the party and left on March 2 1988. A major task of the Expedition was to carry out a complete census of Heard Island's breeding population of Southern Elephant Seals. This task was done in the middle of October, when the numbers of cows hauled out to pup on the beaches were at a maximum and counts made at that time were sensibly referable to other years and other islands. It was the first total census ever completed on Heard Island although one made in 1985 was nearly so. The party was able to walk to Long Beach and census that area. and the availab1l1ty of a helicopter for two days allowed the total photographic coverage of Spit Island, a sedimentary island little more than a metre above sea level and about a kilometre to the east. This island is home to several thousand seals. The one photographic run over this island on October 18 produced a 70mm film record. and thus the whole Island census was completed. Although strong winds during the photography prevented complete overlap of all the aerial photographs. allowance for the small proportion of missed ground was made in censusing. The final total for Spit Island was 3,200 plus or minus 150 cows. A number of other whole Island Southern Elephant Seal counts (excluding Spit Island) were made at intervals of approximately a month so that seal numbers at particular sites and dates could be compared to historical records for these same places at equivalent seasonal times. These counts also gave quantitative measures of 'seal abuse' to coastal vegetation. A daily count of all Southern Elephant Seals in the Four Bays area was maintained for two months. This work enabled the day of maximum numbers to be calculated with precision, as well as providing a detailed record of the haul-out pattern for comparison with other years and islands. The day of maximum numbers, 17 October, was two days later in 1987 than in 1985. The results also indicated a further small reduction in the pup production of the Four Bays area, compared to 1985. However a complete enumeration of the seals on all island beaches still waits on a careful checking of all data. Another Southern Elephant Seal study was the weighing of weaned pups. About 400 pups were weighed at each end of the Island. The total (821) is a considerable data set and it demonstrated the variation in sex ratio and weight through the weaning period. Male pups had a mean weight of 116.5kg (408 animals), and female pups had a mean weight of 111.6kg (413 animals). These data allow real comparison with weaned weights from other islands and thus may provide insights into the reasons for the decline of seal numbers on some islands (the Indian Ocean Sector) and not others (South Georgia). Sixty Southern Elephant Seals. newly arrived at the beach to moult, were anaesthetised, measured and weighed before having their stomach contents flushed out by water through a soft rubber hose. These collections contained obvious examples of squid beaks and stomach worms but await analysis. This will provide the first detailed information on the diet of these seals in the Heard Island area. Leopard Seals were counted whenever they were seen, and at times (late February) they out numbered Southern Elephant Seals on some beaches. Thirty five animals were anaesthetised. measured and weighed before being tagged and their blood sampled. A surprise was the discovery of two Subantarctic Fur Seals bearing tags from Marion Island. This was the first record of this species on the island. Also surprising was the very large number (in excess of 10,000) of Antarctic Fur Seals hauling out in late February. They are not a rare Sight on the Island any more! A detailed study of the attendance patterns of lactating cows and the corresponding weight gains of their pups was carried out. An archaeological survey of the Corinthian Bay sealer's shanty and a botanical study of pool complexes in the north west of the Island were studies undertaken in the first month on the Island. A great deal of effort was also put into censusing birds. A thorough survey of the distribution of all burrow nesting seabirds was completed for the Island and the population of Gentoo Penguins was counted (16,500 pairs in 60 colonies) as well as having the breeding success of their chicks recorded. The colonies of King Penguins were recorded regularly, and appear to be continuing to increase in numbers. 1987/88 was a good season for the Heard Island Cormorant too, as 94 chicks were fledged, compared to six in 1986/87. A large number of banded seabirds were resighted. These Included Subantarctic and Antarctic Skuas, Wandering and Black-browed Albatrosses and a Cape Petrel. Many of these birds had been banded on other islands, away from Heard Island. Nearly all colonies of Southern Giant Petrels were visited and the counts of these colonies showed a near 50% decline compared to 1963. However, 19 breeding birds, banded as chicks in 1963, were resighted. These 25 year old birds give evidence of the long life capabilities of this species. The breeding success of a colony of Black-browed Albatrosses was also recorded. The vegetation of the Island was mapped in detail, and growth studies carried out at a number of dispersed sites. The recognition of another possible species of grass in some newly exposed morainal areas suggests that the retreat of glaciers on the Island is creating new areas suitable for colonisation. Comparison of the vegetation of Heard Island with that of climatically less rigorous Macquarie Island promises to throw up a number of ecologically interesting insights. Many minor projects were also completed (particularly in view of the extra month on the island due to the loss of the Nella Dan) and these included a tethered kelp experiment to discover the plants capabilities as platforms for long distance transport of marine invertebrates. A comparison of the Collembollan (insect) populations in different habitats and the collection of funnel extracted invertebrates in some quantity may extend the species list for the Island. Five more sealers' shanties were discovered around the Island and the artefacts in their vicinity were recorded. A detailed study of casks remaining from sealing days was undertaken, and showed that most originated from the period (1881) when the shipwrecked sailors of the Trinity were living on the island. A windlass was uncovered at low tide, after a storm on Spit Bay Beach, and was returned to Australia. The lengthy period on the Island and enthusiastic assistance from the passengers of relief ships enabled a significant volume of debris from the old station to be picked up for return to Australia for disposal. The tide gauge lost in 1985 was washed up on the beach and was recovered still in a watertight condition. Twelve oceanographic drift cards were found on the beaches and a complete collection of all ocean debris (other than wood) was made from the beaches. East European fishing floats were still dominant items, and indicate the fishing effort in the area up-current from Heard Island. The 1987/88 ANARE was a long expedition for 'a summer', as nearly six months were spent on the island. But this considerable period allowed a very thorough and unusually comprehensive assessment of the status of vertebrate populations and of the distribution of plants.

  • 1992 Wintering Field Season at Heard Island. Taken from the report: Genesis of the Expedition The concept of the 1992 expedition arose from the need to gain access to animals at Heard Island for research at precise times of the year to deploy and retrieve time-depth recorders. An Antarctic Science Advisory Committee workshop on the Southern Ocean Ecosystem was held on 10-11 September 1989 to discuss future plans for ANARE areas of operation. The workshop was attended by myself (KG - Ken Green) and Harry Burton (HRB) for the Land-based Biology section. It became apparent that the two consecutive summers needed to deploy and retrieve the recorders (one leaving Heard Island in the autumn, the next arriving early in the spring) could not be accommodated in the planning process because of planned commitments in the eastern sector of the Australian Antarctic Territory. The suggestion was therefore made by us that if two summers were impossible then perhaps the best solution was a wintering party. A memo to this effect was drafted by us and submitted on 26 September 1989. This was considered at a Heard Island Committee meeting on 18 October 1989 when changes to the shipping program were suggested that would allow two consecutive summers on Heard Island and it was concluded that "this arrangement should.....negate the need for a wintering program in the near future". The suggested rearrangement did not fully match the times required and the Land-based Biology section was loathe to deploy equipment in one summer without guaranteed access to the animals in the following spring. It was felt that this could only be assured if the biologists were on the island through the whole period. An additional advantage was that dietary studies of the main fish predators could be continued throughout the winter period. To this effect the proposal for a wintering party was re-submitted on 26 February 1990 with the suggested personnel being three biologists and three people in support. The proposal was re-submitted in more detail on 4 May 1990 and was examined by the ANARE Annual Planning Committee who referred it to the Assistant Director (Science) to "examine the options for conduct of this program and that following this the Heard Island Planning Committee and to the Assistant Director (Science) who was requested to prepare a paper for distribution to committee members for consideration at a meeting to be held on 17 July 1990. At this point the maiden voyage of the Aurora Australis took place with one aim being to deploy a party of four on Heard Island for a period of one month to undertake research into seals and penguins. This party included two of the subsequent wintering party (see Green 1990). This expedition returned in time for the Heard Island Planning Committee meeting which was held to hear reports on the 1990 expedition and to consider the proposals for 1993. A reduced complement of four expeditioners was suggested in a proposal appearing under the signature of the acting Assistant Director (Science). The committee voted to forward the proposal to the ANARE Annual Planning Committee on 26 July 1990 with the suggested alteration in timing so that the wintering expedition occurred in 1992 rather than 1993 to avoid clashing with science requirements for the Lambert Traverse. The ANARE Annual Planning Committee referred the matter to the executive and on 27 August 1990 the Heard Island Planning Committee agreed to "support a limited winter program on Heard Island in 1992 on the condition that it is to be a purely land-based exercise with work restricted to the Spit Bay area" with "a final decision on the conduct of a Heard Island wintering program (to) be made by the Executive in the near future.". Approval was given at the Heard Island Committee meeting of 24 September 1990, subject to approval by the Antarctic Research Evaluation Group (AREG) of the major programs suggested by the Land-based Biology section. At the Heard Island Planning Committee meeting of 12 December 1990 it was confirmed that AREG had provisionally approved the Land-based Biology programs and that the Executive "have supported the program subject to ASAC endorsement of the three proposals put forward." At this stage the Heard Island expedition was expected to proceed on that basis with additional programs to be considered by AREG. From this point the expedition had sufficient momentum to keep going and subsequent meetings of the Heard Island Committee dealt mainly with questions of logistics, infrastructure and procedures (these are covered in Antarctic Division file number 89/754). The final composition of the personnel for the party was not settled until 14 October 1991. The expedition sailed from Hobart on 8 January 1992 on board the Aurora Australis. Assessments of the possibility of landing by zodiac at Spit Bay were made on 24 and 28 January and on 28 January the party was deployed at Atlas Cove using three inflatable rubber boats. For a narrative of the expedition see the Log (later in the report). Scientific Background A commercial Soviet fishery has existed in the Iles Kerguelen region from the early 1970s and catches averaged about 20,000 tonnes per year between 1979 and 1986, dropping to 7886 tonnes in 1987 and 773 tonnes in 1988. Before 1978, the benthic species Notothenia rossi and N. squamifrons were mainstay of this fishery. The icefish, Champsocephalus gunnari increased in importance after that to constitute the majority of the catch. There has been little commercial fishing around Heard Island, and none since a 200 nautical mile Australian Fishing Zone (AFZ) was declared in 1979 (Williams and Ensor 1988). Catches of icefish by the Soviet research vessel RV Professor Mesyatsev on banks to the north-east of Heard Island indicated concentrations of this species in commercial interest, but other species, including benthic fishes also occurring in the diet of the seals, are not sufficiently abundant for commercial interest at this time (Williams and Ensor 1988). Results from the 1987/88 Heard Island ANARE suggested that there was a potential for competition between the increasing numbers of Antarctic Fur Seals and any future commercial fishery (Green et al 1990). Winter data were, however, lacking. In 1990 the first ANARE expedition to be present on the island into the winter period since the 1954 wintering expedition took place, with the main program being an attempt to examine the winter diet and feeding areas of Antarctic Fur Seals. Subsequent assessment of the diet of Southern Elephant Seals comparing Macquarie and Heard Islands (Green and Burton in press) also showed this species to be a potential competitor, both with Antarctic Fur Seals and with a potential fishery. Bearing in mind the possibility that a request for commercial fishing rights within the Heard Island AFZ might be made in the foreseeable future, probably as an adjunct to the Kerguelen or Antarctic fishery rather than a new venture, a full assessment of the role of fish predators was indicated. The analysis of a potential interaction between wildlife and fisheries depends on the collection of three primary sets of data: the availability of commercial fish species, the diet of the predator, and the spatial overlap in the demands of the two competing interests. The aim of the 1992 ANARE was therefore to collect all of these data. The Marine Science cruises to the area collected data on fish location and relative abundance, continuing the work of previous voyages such as Professor Mesyatsev and the Aurora Australis on its maiden voyage. The work of the shore party would be to investigate the diet of fish predators through scat collections and examination of stomach contents. The main objectives of the 1992 ANARE program on Heard Island were therefore to collect data on the feeding ecology of the major warm-blooded predators of fish in the Heard Island region (excluding whales), to provide baseline data in their ecology in the absence of a nearby fishery, and to provide an estimate of the degree of interaction between these animals and a potential fishery. This was considered to be a major scientific program, both in resources and time and was expected to net valuable scientific information from a very small deployment of personnel. In addition to the main objectives, a number of additional research programs were to be conducted by the wintering party including meteorological observations, glaciology, coastal erosion surveys and marine debris surveys. Field Party Erwin Erb, Medical Officer Ken Green, Biologist Geoffrey Moore, Biologist David Slip, Biologist Attila Vrana, Engineer